I usually do it carefully with a metal scraper, just be sure to keep it flat and straight so it doesn't dig in but if it isn't to stuck you might get it with a stiff piece of plastic. I then give it a clean with a bit of petrol or something similar on a clean rag. You can put something in the bores to catch any crud. The main thing is to take your time and go carefully. Also here's a faq for removal.
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